Hearing aid having a molded chassis



Aug 28, 1956 R. E. TREslsE ETAI- 2,761,018

HEARING AID HAVING A MOLDED CHASSIS Filed March 2, 1949 2 Sheets-Sheet l7/ n \\v\\ INVENTORS 23 RALEIGH E. TRE5\5E Z/ PAUL. D. KENDALL wm #einemAffornes Aug. 28, 1956 R. E. TREslsE ErAL 2,761,018

HEARING AID HAVING A MOLDED cHAssIs Filed March 2. 1949 2 Sheets-Sheet 2INVENTORS RALEIGH E. TRESISE PAUL D. KEN DALL United States Patent()"Tice 2,761,018 rmARING Am HAVING A MOLDED CHASSIS Raleigh E. Tresise,Cleveland Heights, and Paul D. Kendall, Orange Village, Ohio, assignorsto Paravox, Inc., Cleveland, Ohio Application March 2, 1949, Serial No.79,4146k 12 Claims. (Cl. 179-107) trical circuit, together with thebatteries providing the power supply therefor.

In a hearing aid, it is particularly desirable to provide a small,compact apparatus since normally such apparatus is carried by anindividual and is generally received in a pocket or other portion of theclothing of the wearer. Hence any bulky apparatus is objectionable and aminimum size element is very desirable. Such a construction still mustnot sacrifice desired operating characteristics and it also should becapable of withstand-ing the fairly rough use to which hearing aids aresubjected.

The general object of the present invention is to provide a novel,compact hearing aid apparatus wherein a special contoured chassis isprovided and has recesses provided therein for receipt of andpositioning of all elements of the electrical circuit of a hearing aid,including the power supply therefor.

A further object of the invention is to provide a molded chassis for ahearing aid wherein the chassis is adapted to reinforce a surroundingcasing at substantially all points.

A further object of the present invention is to secure individualhearing aid elements in recesses provided therefor in a mountingchassis, which elements can easily be inserted into or removed from theSpecial cavities provided therefor.

A further object of the invention lis to provide a positive anchoringdevice between removable portions of a hearing aid electrical circuitand a chassis on which such elements are positioned.

A further object of the invention is to provide insulating covers forretaining hearing aid elements insulated from a carrying case in whichthe chassis is received.

Yet another object of the invention is to provide maximum protection,both physically and electrically, .of the elements of the hearing aidcircuit from a carrying case surrounding them. t

Still another obiect of the present invention is ,to provide indexingmeans on a `Irwuuting chassis for association with a removable hearingaid component to be received in a recess in the chassis.

Another object of the invention is to provide a rigid carryingr chassisfor all of the components of a hearing aid so that iixed electricalcontacts may be provided between the batteries of the hearing aid andthe remainder of the electrical circuit of same.

Another object of the invention is to provide Contact 2,761,018 ientedAug. 28, 1956 plates in a hearing aid which can easily be inserted intoengagement with the chassis by a minimum of labor and with the contactsbeing inexpensively formed and assembled. i

Another object of the invention is to provide a special unitary contactplate for a plurality of batteries in a hearing aid.

Other and more limited objects of the present invent-ion are to providea resilient grounding arm which is formed integrally with a Contactplate of the hearing aid and is adapted to bear automatically upon acarrying case for the chassis of the invention; to provide a path for aconnection for a lead extending from one contact plate in the batterypositioning recess over to theremaining portion of the chassis; toposition a hearing aid element in a complementary formed or sharpedrecess in a chassis so that the element can easily be secured therein;and to provide a simple, inexpensive but positive means for assembling ahearing aid element in fixed position in a positioning chassis. v

The foregoing and other objects and advantages of the invention will bemade more apparent as the specicaf tion proceeds.

For a better understanding of the invention, reference should be had tothe accompanying drawings, wherein:

Fig. 1 is a plan taken on line i-l of Fig. 2 of a hearing aid having amolded chassis and the bottom portion of a surrounding casing shown indotted lines with only a portion of the hearing aid elements being shownpositioned therein, which hearing aid embodies the principles of thepresent invention;

Fig. 2 is a longitudinal vertical section of the molded chassis taken online 2?-2 of Fig. l; :van

Fig. 3 is a fragmentary section of the molded chassis taken on line 3T3of Fig. l to show the battery receiving recess and a speciai contactplate of the invention;

Fig. 4 is a fragmentary vertical section of the molded chassis taken onlined-f4 of Fig. l, of a switch mounted in accordance with theinvention;

Fig. 5 is a fragmentary vertical section taken on line 5--5 of Fig. 8,of a ground contactor;

Fig. 6 is a transverse vertical section taken on line 6-6 of Fig. l withthe exception that the casing is shown sectionally in full line;

Fig. 7 is a transverse vertical section of the molded chassis taken online 7 7 of Fig. 1 to show the positioning of an output connector blockin the hearing aid;

Fig. 8 is a fragmentary bottom plan of a portion of the molded chassisand elements contained ktherein of the invention;

Fig. 9 is a fragmentary Vertical section of the hearing aid taken online 9--9 of Fig. 8 to show a portion ofthe leads extending from theprinted circuit panel shown in Fig. 8;

Fig. l0 is a fragmentary transverse section taken lon line lil-10 ofFig. 8 to show a contact wire leading from the printed circuit panel toa battery contact;

Fig. l1 is a fragmentary section of the outlet connector taken on line11.-11 of Fig. l; and 1 Figs. l2 and-13 are a fragmentary plan and aside elevation, respectively, of a modiiication of the invention.

The present invention, broadly speaking, relates to a hearing aid whichincludes a molded chassis having a plurality of specially contouredrecesses formed therein for receipt and-positioning all of the hearingaid elements, including the batteries, in fixed relation. The vchassisis provided with at least one pair of opposed channels .on one side ofthe battery receiving recess for sliding engagement with a spring metalcontact plate adapted to contact and aid in positioning a battery in thechassis, with other special positioning means being provided in thechassis for engagement with individual hearing aid elements received inthe chassis for retaining such elements in a given position, and withcover means being provided for at least some recesses and the elementstherein.

Reference is now made to the details of the structure shown in theaccompanying drawings and in this instance there is shown a hearing aidelement indicated generally by the numeral 2t). This hearing aid elementor apparatus includes a special substantially rectangular mount- 1ngchassis 21 which is formed from any moldable insulating material whichmay comprise one of the usual plastic materials, rubber, wood or thelike and, speciiically, might comprise a cellulose acetate butyratematerial such as Tenite The chassis 21 is of appreciable depth, isusually rigid and strong, and is formed of a predetermined contour andhas an externally shaped periphery substantially complementary to theinside contour or shape of the carrier case in which the chassis 21 isto be received for use. Normally the carrier case will be formed from arelatively thin material which will be reinforced by the chassis 21. Thecarrier case, as shown in Figs. l and 6, having a bottom section 114,and a top section 115 is in close fitting engagement with the chassis21. The casing may be readily removed by providing an interlockingtongue and groove connection 116.

Another feature of the chassis 21 is that in forming or molding same aplurality of desired specially contoured recesses may be provided inwhich different hearing aid elements may be positioned. One recess 22 isof substantially rectangular contour and may be considered to be formedin the face surface of the chassis, and it is appreciably larger thanany other recesses formed in the chassis 21. This recess 22 is thebattery or power supply receiving recess for the hearing aid apparatusand is formed in the face of the chassis 21 adjacent one end thereof.The battery receiving recess 22 has a pair of opposed walls 23 and 24partially delining same and the wall 23, as a special feature of theinvention, has a pair of opposed channels, or recesses 25 and 25a formedin spaced end portions thereof for receipt of a contact plate 26therebetween by a telescopic or sliding engagement between the endportions of the contact plate 26 and the channels 25 and 25a. It will benoted that the wall 23 provides an exposed or open surface between thechannels 25 and 25a, whereby a portion of the contact plate 26 mayextend directly therebetween. However, the contact plate 26 also isprovided with two inwardly extending offset contact sections 27 and 28.These contact sections 27 and 28 are resilient and serve to aid inpositioning batteries in the recess 22, as will be hereinafterexplained. The wall 24 dening the recess 22 also has a channel or recess29 formed in one edge thereof. Adjacent the other margin of the portionof the wall 24 forming the recess 22, there is a slot 30 formed in theupper portion of a partition or Wall 31 which defines the inner lateralmargin of the recess 22. Usually to simplify the positioning of twoseparate contact plates 32 and 33 in the recess 22, a separate block orinsert 34 may be secured to the wall 24 intermediate the margins of therecess 22. This insert 34 is provided with overhanging lateral edges 35each of which provides, in effect, a channel or recess between the inneredge surface of the insert 34 and the adjacent portion of the margin orwall 24. Thus the contact plates 32 and 33 can be telescoped intoengagement with the edges of the block 34 and channel 29 and slot 30.

Another feature of the present invention resides in the means used tosecure a terminal or connector block to the chassis 21. Thus a recess 41is provided in the chassis 21 intermediate the ends thereof andextending substantially transversely of the hearing aid. This recess 41has a pair of ribs 42 formed in the bottom surface thereof forseparating different vacuum tubes which are thereafter usuallypositioned in the recess 41. The recess 41 is bounded on one side by thewall 31 and on the other side by a second partition wall 43. One endportion of the recess 41 extends to the side edge of the chassis 21 andis open at such end for receipt of the tubes to be secured therein. Theinner end of the recess 41 has a plurality of abutments 44 and 45terminating same, the outer surfaces of which lie in substantially thesame horizontal plane as the outer surface of the wall 31. Theseabutments 44 and 45 each have a channel 46 and 47, respectively, formedin opposed edge portions thereof and extending the height thereof beingopen to the exposed face of the chassis 21. The adjacent portion of thewall 31 is thickened appreciably adjacent the abutments 44 and 45 andhas a channel 4S formed therein similar to the channels 46 and 47. Theabutment 45 also has a channel 49 formed therein and the channels 43 and49 are formed so that they are in opposed relationship whereas thechannels 46 and 47 are likewise in opposed relationship and are openfrom one margin of the chassis 21. Thus a properly shaped hearing aidelement can be slid into engagement with either pair of channels desiredso as to position such hearing aid element, such as a socket orterminal, or contacter block 51 between each pair of channels. Thesockets 51 have lugs 5l"L formed on opposite sides thereof forengagement with the channels 46 and 47, and 48 and 49.

An important feature of the present invention is that the wall 31, andthe abutments 44 ad 45 all have what may be cosidered to be a continuoushole 52 formed therein. This hole 52 extends completely through the wall31 and the abutment 45 whereas it only extends partially into theabutment 44, as indicated in Fig. l. Thus a pin 53 can be telescopedinto engagement with the hole 52 from the side of the battery receivingrecess 22. The pin 53 then normally will overlie the sockets 51 whichare in engagement with the respective channels referred to hereinbeforeto retain same therein.

As another important feature of the present invention, an outputconnector block 54 is in snug engagement with an elongate, shallowrecess 55 formed in one end of the face surface of chassis 21, as bestshown in Figs. l and 7, in which the battery receiving recess 22 and thevacuum tube recess 41 are formed. This connector block 54 is provided toengage with a pair of jacks or other members used to form a removableoutput connection with the hearing aid of the invention. Hence a pair ofconnector sockets 56 are provided in one end portion of the block 54 andthey connect to a second pair of lead receiving sockets 57 which areformed in another portion of the connector block 54 and are adapted tohave leads or connector means secured thereto from the remainder of thehearing aid apparatus. Another novel feature of the connector block 54is that it is secured in place by a pin S8. This pin 58 is engaged witha hole 59 that is formed in the chassis 21 and with a hole 60 that isformed extending partially into the connector block 54 from the sidethereof. When the connector block 54 is properly positioned, the holes59 and 60 are in alignment and the outer end of the hole 59 is exposedsince it extends from a lateral side margin of the chassis 21.

Fig. 1l of the drawings best shows that the block 54 has a littleprotuberance 54a formed in the base portion thereof and that acomplementary shaped socket or seat 55a is formed in the base portion ofthe recess 55 for receipt of the boss 542L to retain the connector block54 in a fixed position with relation to the recess 55.

Yet a third socket or connector block 61 may be positioned at the innerend of the vacuum tube receiving recess 41. In this instance, a channel62 is formed in a thickened portion of the wall 43 adjacent the abutment44. This abutment 44 is slightly longer than the abutment 45 and in therear portion thereof facing the channel 62, a channel 63 is formed insuch abutment in opposed relation to the channel 62 whereby yet anothersocket or other desired member can be telescoped into engagement withsuch pair of channels 62 and 63. Again, a hole 64 is formed in theabutment 44 and it is in alignment with a hole ,65 that is formed intobut does not extend through the wall 43. Thus another pin 66 may extendthrough the holes 64 and 65 to retain a socket 61 in place. It will Ybeseen that the socket 61, like the other sockets used in the apparatus ofthe invention, usually is smaller in height than the recess 41 andassociated elements whereby the sockets can be slipped down intoengagement -with the associated sets of channels below the :pinreceiving holes formed therein. Thus the pins are located externally ofbut usually in `contact or engagement lwith the sockets, but, if desiredcould extend through a hole in same to secure them in the chassis.

While there have been shown herein sockets having lugs or rails formedon the sides thereof, -in some instances it may n ot be necessary to'use a definite sliding engagement between the chassis and the hearingaid element. Also, the channels may be formed on the hearing aid partand the rails or Ilugs on the chassis, or the element may be solelyengaged with the chassis by the snug t between a special receivingrecess and a hearing aid element. In all events, a pin, when used tosecure the hearing aid element in the chassis, may engage with spacedportions of the chassis and the elements either directlyor indirectly,or with only the hearing aid element and the chassis alone so as toretain a hearing element in a desired recess. @if course, itis desirableto form the hearing aid element and the recess of complementary shape sothat the element can be snugly positioned in a carrying and mountingchassis.

Another feature of the invention is Vthat the contact plate 26 has alittle ear 126 extending -therefrom as shown in Figs. and 8. This ear`126 extends through Va small hole 121 formed -in the chassis 21 andprotrudes therefrom. The Vear 126 is of a resilient construction and isused -for contact with the carrying case Vfor the hearing aid apparatus.The ear 126 then will form a ground connection for both of the batteries4received inthe recess 122.

Another salient feature of the present linvention resides in a recess71, Fig. 2, which is formed in the back of the -chassis 21. This recess71 is of a relatively rectangular shape and is of quite shallowconstruction. The recess 71 lies lbehind the battery receiving recess 22which is relatively deep. The recess 71 receives a -ilat hearing aidelement component such as a lprinted circuit panel 72 therein. 1t shouldbe noted that the -recess 71 has a shoulder portion 73 formed in 'thewalls thereof and extending substa-ntially therearound. Thus after thepanel 72 is positioned in the recess 71, it is possible to place aninsulator or cover panel sheet 74, made from any suitable material, overthe recess 71. This panel 74 is adapted to be supported on the shoulder73 -and may be permanently secured thereto, if desired, Vby cementing orotherwise securing the cover member in position. The panel 72 normallyhas a plurality of leads 75 extending from one end thereof whereas alead '76 extends from the other end thereof, as shown in iFig. 8 andthrough a channel recess 77 and hole 78 to an edge of the battery recess22 where it connects to -the contact plate 26. A special lead 175 mayextend from the -other end of the panel 72 through a recess and hole=176to extend -below the block 34 and connect to the contact 32. Itshould be noted that `the cover 74 smoothly blends in -with theperiphery of the chassis 21 and protects the printed circuit panel fromshorting against the casing or being otherwise dis turbed. The leads 76and 175 -are below the .periphery of the chassis and hence protectedfrom contact with any carrier case used.

1n another portion of the apparatus, a recess 81, best shown in Fig. 6,is provided for receipt of a portion of a connector circuit includinganother printed circuit panel 91. This recess 81 is relatively deep vandit `has a plurality of leads received therein, primarily from thesockets 51 and 61. A cover 82 is provided for blending into theperiphery of the chassis 21 and forming aprotective cover for the recess81 and the electrical means received therein. The cover 82 may besupported on the chassis in any desired manner. In -this instance, ajlittle extension lug 83 is rformed on one side of the cover `82 and itmay bear upon either wall 31 or, usually, an elongate tone controlswitch 84 which is positioned in the wall in a recessed portion thereof.This recessed portion 85 of the wall 31 is provided with a pair ofspaced but opposed channels 86 which are adapted to engage with endportions of the switch S4 whereby such switch can be ,slid into snugtelescoped engagement with the recess 85 and be retained in suchposition. An larcuate inner edge portion 87 is also provided on thecover 8 2 and itvprotrudes down inwardly with relation to a lateralmargin of the chassis 2 1. The cover 82 also -is Asupported at its inneredge by bearing on the sockets 51 and 61. "The edges of the wallsforming the recess S1 may `have supporting shoulders formed thereon, ifdesired, or suitable elements may be used to retain the cover 82 securedto adjacent portions of the chassis 21.

Fig. 4 best shows that the switch 84 may include a pivotally movablecontact arm 88 which has an extension 89 formed thereon for engagementwith contacts 90 .provided on base portions of the switch 84. A portionof the contact arm 88 protrudes above the periphery of the chassis 21 topermit the position of the switch to be readily controlled from a pointlexterior to the chassis.

In the drawing, there are shown a plurality of other recesses formed inthe chassis 21 and the -particular shape and spacing or size of suchrecesses and the elements (not shown) received therein are not parts `ofthe present invention. The chassis 21 has apertures or slots or recessesprovided therein where itis desired to pass conductors from `onerecessed portion thereof to another so that the conductors are retainedwithin the contour or periphery of the chassis.

Yet another method of mounting hearing aid elements or apparatus in -arecess inthe chassis used in the vinvention is shown in Figs. 12 and 13of the drawings. In this instance a molded chassis is providedwith aspecially contoured v recess 101, Ywhich would usually vhave a yfiatbase surface 102. The recess 101 is specially contoured and is shapedcomplementary to the bottom surface of a hearing aid element such as asocket 103. This socket 103 has a plurality of leads 104 extending intoone `side thereof which leads may extend from a vacuum tube, and aplurality of leads 105 extend from the other side thereof so that -thesocket member 103 can be used to connect any desired set or sets ofconductors forming part of the hearing aid apparatus of the invention.Usually the side walls of the recess l1 01 are substantially verticallydirected with relation to the longitudinal axis of the chassis 100whereas when the corresponding side portions of the socket 102 aresimilarly contoured to provide a snug engagement between the recess andsocket. The end portion of lthe chassis v100 may also position a controlswitch 106. As indicated in Fig. 13, this switch 106is located belowvthe vertical position of at least the upper portion of the socket 103,so that a pin 107 can be engaged with laligned holes 108 and 109 formedin the upper portions of the chassis 100 defining the recess 101.Usually the hole 109 extends completely through a wall 110 in thatportion of the chassis 100 whereas the hole 108 only ,extends into thebody portion of the chassis adjacent the other side of the recess 101.Hence the pin 107 can be threaded or telescoped into engagement with4the holes 109 and 103 from the edge or corner portion of Ithe chassis100 after the socket 103 is slid into kposition in the recess r101. Ifdesired, complementary shaped bosses and recesses could be formed on thesurface of the recess 101 and the lower portion of the socket 103 toretain same against any movement longitudinally of the yrecess 101 since.the other positioning of the socket V103 in the recess prevents actualdisengagement of the socket from the recess.

The drawings also clearly show in Figs. l and 2 that batteries A and Bmay be positioned intermediate the contacts 32 and 33 and the offsetportions 27 and 28 of the contact 26. Hence a resilient but eectivesupport is provided for the batteries A and B and the same areeasilyinserted in or removed from engagement with such mounting andcontact means.

It will be realized that the insert block 34 referred to hereinbeforemay in some instances be formed -integrally with the chassis, ifdesired. In some instances the undercut referred to hereinbefore in thebase of the block 34 may be omitted, if it is not required in thechassis. The printed panel members 72 and 91 referred to hereinbeforeusually include exposed contact means or Wires whereby it is desirableto insulate same from the remainder of the apparatus. Of course, thecover panels used in the apparatus can in some instances be cemented inplace merely by having cement positioned between two adjacent abuttededge surfaces one being on the cover panel whereas the other surfacewould be formed integrally with the chassis itself. Of course, spacedlugs or shoulder portions may be used in place of the continuousshoulder 73 disclosed herein.

By virtue of mounting all of the elements of a hearing aid on thechassis 21, the chassis will form a completely operative structurewithout the addition of any other elements thereto hence the hearing aidwould Work without a cover or carrying case provided therefor as long asa ground or connector wire would be provided between several diierentleads of the apparatus which at present are connected -through thecasing in which the chassis and elements are to be inserted. It shouldbe noted that, in general, all of the components of the hearing aid arereceived completely within the periphery of same to prevent contact withthe carrier case so that the operating elements are insulated from thecarrier case which provides a ground element for the apparatus.

This present invention is a continuation in part of our joint co-pendingapplication Serial No. 732,718.

Reference also is directed to our other joint co-pending applicationSerial No. 762,278 which shows a typical casing construction used toencompass the chassis of the invention.

By positioning the power supply batteries and all the remaining elementsof the hearing aid in specially shaped recesses formed in the chassisot' the invention, one is able to effect a positive location of therelative hearing aid elements and the connections between the batteriesand other hearing aid elements are made by iixed conductors.Furthermore, the particular type of contacts used with the chassis ofthe invention facilitate positioning the batteries on the chassis and aready connection means is provided for taking current from thebatteries.

Any of the indicated means may be used in locating hearing aid apparatusin a specially shaped recess adapted to receive same and then a pin canbe used with either the hearing aid apparatus itself and with themounting chassis, or with just the chassis, as desired so as to lock orretain the hearing aid element in a given position.

Usually the retaining pins are retained in a given position f by asuitable cement. However, when required, both the locking pins used inthe invention and the respective covers can be disengaged from theremainder of the chassis to permit repair or replacement of the hearingaid elements of the apparatus.

Having thus described our invention, what we claim is:

1. In a hearing aid, a molded chassis having a plurality of recessestherein for receiving and -carrying hearing aid elements therein, saidchassis being formed to provide a battery receiving recess in oneportion thereof `open from one face of said chassis and including a pairof opposed sides, said battery receiving recess ibeing relatively largeand one side formed with one pair of spaced lbut opposed channels andwith tw-o pairs lof spaced but opposite channels on the opposite sidethereof, and spring contact plates disposed in slidable engagement withsaid channels in said battery receiving recess and positioned therein bysaid channels, 'a carrying case having thin walls lfor close engagementwith said chassis, said chassis being adapted to be inserted as a unitinto said carrying case.

2. A molded chassis for a hearing aid having `a plurality of lrecessestherein for receiving and carrying hearing aid elements therein, saidchassis being formed to provide a recess in one portion thereof one wallof said recess being formed to provide a pair of spaced parallel andopposed channels `for slidable receipt of the end portions of 'a springmetal contact therein, two batter-ies positioned in said last namedrecess and a common contact plate for said ibatteries the end portionsbeing engaged with said channels and having ltwo longitudinally spacedcontact sections provided thereon each of which individually engages oneof said batteries, a thin carrying case yfor close engagement with saidchassis, said contact plate having a portion extending therefrom themargins of .the `chassis to prov-ide spring electrical contact with saidcase.

3. A molded chassis for a hearing aid having a plurality of recessesformed therein 4for receiving and carrying hearing aid elements therein,a hearing aid element having a Ibody portion lformed to provide a holetherein positioned in one of said recesses, said chassis Ibeing formedyto provide a hole both lends of which are exposed in the portionthereof adjacent said recess, and a pin engaged with the hole in said`chassis and extending therefrom to engage the hole in said hearing aidelement to retain same in its position in said chassis.

4. In a hearing aid, a molded insulated chassis body formed to provide arecess therein for receipt of a connector block, a connector blockdisposed in said recess, said chassis and block each being formed toprovide holes in alignment with each other extend-ing thereinto from anexposed portion of said chassis, and a pin in said aligned holes toretain said lblock in position.

5. A molded chassis for a hearing aid formed with a recess in oneportion thereof said recess having a pair of spaced parallel and opposedchannels formed therein open at one edge of the recess, and a terminalyblock smaller than ysaid recess and having a pair of protruding lugsformed on opposite sides of same, said lugs being in slidable engagementwith said channels to position said block in said chassis lbelow theouter margin of the recess, and a pin extending across the recess andengaged with said chassis to retain said block in said recess.

6. A molded chassis body for a hearing aid formed to provide a pluralityof recesses therein for receiving and carrying hearing aid elements,said chassis being formed to provide a recess in one portion thereofwith a pair of spaced parallel and opposed channels, a hearing aidelement having a pair of protruding lugs formed on opposite sides ofsame, said lugs .being in slidable engagement with said channels andheld thereby to position said element in said chassis, said :chassisbody being formed with aligned holes therein on both sides of saidelement receiving recess, and a pin engaged with the holes in saidchassis and extending across said recess Vto retain said element in itsposition in the channels in said chassis.

7. In a hearing aid, a molded insulating chassis body formed to providea Ahearing aid element receiving recess therein, a hearing 'aid elementsnugly received in said recess and being shaped substantiallycomplementary `thereto, and a pin engaged in said chassis and extendingacross said recess to retain said element in position.

8. In a hearing aid, a molded insulating chassis having a recess formedtherein with a pair of spaced but opposed walls at least partly definingthe saine, said walls being formed with opposed channels therein open tothe outer surface of the chassis and extending in the direction of thedepth of the recess, a hearing aid component received in said recess andengaged with said channels, said chassis being formed to provide a holetherein one end of which extends through the portion defining said 9recess, and a pin received in the hole in said chassis and engaged withsaid component to retain same in said recess.

9. In a hearing aid, a molded insulating chassis formed to provide arecess formed therein With a pair of spaced but opposed walls at leastpartly defining the same, a hearing aid component disposed in saidrecess, said chassis body being formed to provide a hole therein one endof which extends through a portion thereof defining said recess, and apin received in the hole in said chassis and engaged with said componentto retain same in said recess.

10. In a hearing aid, a molded insulating chassis having a face andhaving a plurality of hearing air element receiving recesses formedtherein one of which is adapted to position a pair of batteries thereinand is formed in the face of the chassis, and includes a wall portion,an insert block secured to the wall of said recess but being spaced fromthe bottom thereof and having overhanging side portions, said Wall beingformed to provide a channel type contact receiving slot in spacedportions thereof one on each side of said block, and a contact plate insliding engagement with one of said slots and with an overhanging sideportion of said block.

11. A hearing aid as in claim wherein one member of said chassis andsaid block has a protuberance formed thereon and the other of saidmembers has a recess formed thereon for receipt of the protuberance whenthe said block is correctly positioned in said recess.

12. A hearing aid comprising a chassis of molded plastic material formedWith recesses therein for the reception of hearing aid elements, saidchassis being in Substantially the form of the completed hearing aid,and a readily removable cover of thin protective material surroundingand enclosing said chassis in substantial engagement therewith andprotecting the chassis against physical damage, said chassis beingformed and providing a substantial close fitting contact with the coverand engaging said cover to provide a substantial support for the coveragainst deformation of the cover.

References Cited in the file of this patent UNITED STATES PATENTS Re.23,203 Posen Mar. 7, 1950 1,630,028 Reynolds May 24, 1927 1,805,362Ellis May 12, 1931 1,811,638 Lieber `lune 23, 1931 2,176,671 Huth Oct.17, 1939 2,268,619 Reid Ian. 6, 1942 2,306,707 Mason Dec. 29, 19422,308,550 Shapiro Jan. 19, 1943 2,327,320 Shapiro Aug. 17, 19432,327,321 Shapiro Aug. 17, 1943 2,333,028 Merrill Oct. 26, 19432,336,828 Zarth Dec. 14, 1943 2,444,302 Lybarger June 29, 1948 2,482,288Posen Sept. 20, 1949 2,495,476 Posen Jan. 24, 1950 2,495,546 Posen Jan.24, 1950 2,496,683 Tresise et a1 Feb. 7, 1950 2,497,336 Young Feb. 14,1950 2,500,301 Tresise et al. Mar. 14, 1950 FOREIGN PATENTS 834,981France Sept. 12, 1938

